Photographic emulsions containing pseudocyanine dyes and 9-methyl thiacarbocyanine dyes



PHOTOGRAPHIC` EMULSIONS CONTAINING PSEUDOCYANINE DYES AND Q-METHYL THIACARBOCYANINE DYES Filed Feb. 9, 1945 NOV 4, 1947. E. E. NICHOLSON ET AL 2,430y072 ATTORNEY Patented Nov. 4, 1947 nariz PHOTOGRAPHIC EMULSIONS CONTAINING PSEUDOCYANINE DYES ANI) S-METHYL THIACARBOCYANINE EYES Ernest Edward Nicholson and Ronald Bernard Collins, Ilford, England, assignoi's to Ilford Limited,

Ilford, England, a British company Application February 9, 1945, Serial No. 577,034 In Great Britain February 1 1, 1944 8 Claims. 1

This invention relates to photographic emulsions and particularly to the manufacture of dyesensitised photographic silver halide emulsions.

Photographic silver halide emulsions have a certain natural sensitivity to light, but this is restricted to a short range of wavelengths in the ultra-violet and/or blue regions of the spectrum. The eiiect of incorporating a sensitising dye is to impart to the emulsion sensitivity to light of other wavelengths. It has been known for sometime 10 general structure that the effect of incorporating in the emulsion, y together with a sensitising dye,A a second sub- /X stance which may or may not itself be a sensitizer, sometimes imparts an additional sensitivity to C-CH N the emulsion beyond that which can be regarded l5 as the sum eiect of the separate substances. R Combinations of sensitising dye and another sub- R A Stance Wlicfh. give tm? latper result are known as where R is an alkyl or aralkyl group, A is an acid Supersetstmsmg combmatmns radicle and X is an oxygen, sulphur or selenium In, Bimsh paient, No' 498290 .Valleys Super' 20 atom. The carbocyclc rings of either or both sensitising combinations are described, including, nuclei may Contain substituent groups if desired among mlny Others the @O mbma'twtl of a e. g. fused benz groups, hydrocarbon groups, pseudocyanine and a carbocyanine containing an alkoxy groups amino groups or halogen atoms; 'Y A alkyl substituent 1n the central carbon atom of The Q alkyl thacarbocyanine dyes employed the trimethme chain. These latter compounds have the general structure are referred to in the said patent as 8-alkyl compounds, but are referred to in the present speci- /S R, S\ cation (using the system of numbering which is \\C CH CH C/ now preferred and is used in the recent authoritative work Theory of the Photographic Process \N/ N/ by Mees, published by Macmillan & Co. (1942) as i the 9-alkyl compounds. A R1 It is stated in the said patent that the relative Where Ri is an alkyl or aralkyl group, A is an acid quantities of the said two types of compound may radiele and R2 is an alkyl group. The carbo- Vary, fOr example from 1:5 to 5:1. 35 cyclic rings of the thiazcle nuclei may contain It has now been discovered that a very valuable substituent groups ii desired, for example any of supersensitising eliect may be obtained by the those mentioned inthe preceding paragraph. combination with an oxa, thiaor selena- The acid radicles A in the two dyestuffs may be, pseudocyanine dye of an extremely small quanfor example, halogen atoms, alkyl sulphate, alkyl tity of a 9-alkyl thiacarbocyanine dye, and ac- 40 p-toluene sulphonate, or perchlorate radicles, C01dng to the present IIVGHOD, thelSfOre, the iodide and bromide radicles being generally photographic silver halide emulsions are superpreferred. The groups R, Ri and Rz are prefersensitised by incorporating in the emulsions an ably lower alkyl groups, e. g. methyl or ethyl, oxa, thiaor Selena-pseudocyanine dye in a propyl or butyl, though they may be higher alkyl quantity which alone is suilicient to impart good groups. colour sensitivity to the emulsion, together with The following examples illustrate the invena 9-alkyl thia-oarbooyanine dye in a quantity tion. In thesev examples emulsions containing which alone would be insuflicient to impart any the pseudocyanine dyestuff alone and emulsions useful colour sensitivity to the emulsion and containing the pseudocyanine dyestuff together which is not greater than about l/fiu of the weight with the 9-alkyl thiacarbocyanine dyestuff were of the pseudocyanine dye employed. tested for speed to daylight and to yellow light. The optimum quantity of the pseudocyanine This latter figure was obtained by exposing the dye will vary with the particular emulsion, but test emulsions to white light passing through a Will generally be of the order of 450- cc. of a lter which cuts off all radiation of wavelengths 1 in 1000 solution of the dyestui per 10 litres of 55 less than 520 m/i and the increase in the yellow emulsion. The quantity of the 9-alkyl thiacarbocyanine dye will accordingly be of the order of 11/4 to 2%; cc. of a 1 in 1000 solution per 10 litres of emulsion. The invention is of special importance in connection with gelatino silver bromide emulsions, including silver iodobromide emulsions, but may also be employed with emulsions containing silver chloride.

The pseudocyanine dyes employed have the 3 4 speed shown by the supersensitised emulsions in process described in British Patent No. 498,290 comparison with the emulsions containing only that very much smaller quantities of the superthe pseudocyanine dye aords a measure of the sensitising dye are required, with consequent ecosupersensitising effect obtained. nomic advantage. The results obtained by the Emmpzes 5 presentinventionare surprising in View of the fact .that the .quantity ofsupersensitisingdye em- In these examples the following dyestuffs Were pioyed is so Smau that used alone it does not @1111310576612 impart any useful colour sensitivity to the emul- Pseudocyanine dyestufs: A Sion- A. 1.1'aiethyi2.2'quinocyariine10eme.V 10 Whatwefaim isi B. 1.3-diethyl-'chloro-thiaquino(2.2)cya, 1 Aiphotographiczsilver halide emulsion connine 0dide taining a pseudocyanine dye selected from the C 1 3' dethy1 thaquino(227)Cyanineiodd class;consisting;of:oxaf, thiaand Selena-pseudo- D 1 3 diethy1 5f methy1;.se1enaqum0(2521:) cyanineeidyes inria;quantity which alone is suffi- Cyanine i0dide i 15-cient2to impartwgood colour sensitivity to the emulsionfltogethenvvith a 9-alkyl thiacarbocy- 9'lky1 thaCarbOCya-nne YCSUSI- aninefd'yein aoiiantity which alone is insufficient P- 3-3'9-fmelihyl-thiaarb()Cyanine iodide. to impart any substantial colour sensitivity to Q. 3.3dthy19 methY1-haCaIb00YaHiI-e--' the-emulsion and which is not greater than 1lo iodide. 20 and not less than l/zo of the weight of the pseudo- R; 3.3".9'-trethyl-5-5(ci :l1lox'othiacarbocyaV cyan-ine dye present'.-

ninebromide: 2; Afphotographic silverlhalideremulsion con-A S; 3.3'dethyl-9-mthy1-4.5.4^.5'-dibenzfthie tainingia pseudoeyaninee-dye seleetediroin the acarbocyaninebromide. classconsistingof oxa'-, thiaand Selena-pseudo- Tl 3:3fdithyl*9:5.5'PlirlflftliylShiaCLltbOCsr-Y 25: cyanine-dyesin a-quantityof 0.05 toV 0.1 grain` anineiodde.'` per 10 litresfof` emulsion, together with a-9'a1kyl thiacarbocyanine dyevin a-1z1uantity which alone# is insufficient to impart any.- substantial ycolour sensitivityto? the emulsionandwhich is=not` ogreater than-1A@v and not less. than 1/120 lof'the weightof the 'pseudooyanne dye 'present'.

3.- A photographic gelati-no(4 silverY bromide emulsion.containing:apseudocyanine'dye selected l from theeclassf consisting; of. oXa-, thiaand- Tlie combinations of-dyes were incorporated in a silver.` iodobromide emulsion containing about 6.5 gms. of silver halide (calculatedlas silver) per litre of emulsion, during the manufacture of the emulsion, and the' resulting emulsion was coated on glass and the speed values'referred to above were determinedi The-results are setiout in the followmg table? 35 selena -pseudoeyaninedyesiir-y a :quantity whichvr alone is ,7 sufcent to" impart 1 goodtcolour sensi- Quantity VQfugnltligi tivity tofthe-emulsioml together with ya` Q-alkyl'` OfPSeildw Q alkyl hia'e, thacarbocyaninedye-in'- laquantityfwhich alone Jingle Ei dggigs ctargf 'dgiircl ggg is insucient to impartanysubstantial colourV NU... dye, Waning. 1:29001 Speed spee 40.v sensitivity to the .emulswn and'whiohis not perline.. l dye Solution greater than 1&0 Vand Anotiessl chanel/12o offthe 2 Ofermlliml f'lltsr weight of-the-pseudocyaninedye-present.

4; A photographic gelatinesilver: bromide 1m, A, 6 5 85 g emulsion containing a'pseudocyanine dye selected Y. 1b A (i5 P' 0-25 125 51 45 fromvtheeclass` consisting of oXa-, thiaand' 2a A 6 5 107 7 selenafpseudocyanine dyes:of-*0.05-to-0.'1 gram` 'gb-7 A" @-5 Q7 0,25 118 34 perl() litreslofffemulsionatogether with' a 9-alkyl A 6.5 R 0.25 112k i7 2d A 6 5 s 0 25 170: 57 thiaearbocyanineedye 1n afquantity which. alone 28 A 6:5 'Th' 0 25 150i 38 is.insuicient-tof impart any substantial colour 3a B` 10.0 l. 155 14 50"'fsensitivity toftheeemulsonandfwhichiis not'-l 3b B` 10-0 P 0-25 180 37 greater thani'/io andfnotless .thaniao ofathel-r 4a C 7.5 n125 17 weight of the pseudocyanine'dyepresent.v y 4b^--- C *T5 P 0:125 125- 26 5,A1 photographic gelaftinoi silverf bromide all--. 'vn- W 6;5 185A sil emulsion'.cont-aininga-pseuolocyaninedyeselectecl.`` 5b D f5-5 ,V185 'A 56'f55ffrom the class consisting -,o f-joXa-; fthiaand Y, Y c c selenarpseudoyaninedyes-ein;aquantty which The :speed valuesggiuengin thegforegoingvj-,ablef alone is sufeient to impartgood-colour sensi-' areisubstantiallylinearlyrelated, i-.re.-ar,evindirect tivity-to the emulsion,qtogether.with aV thiacarproportion-j 'i Y y` Y ,Y bocyanine: substituted linytlfie V.ll-position Vby a- `The isi-1persensitisi-ng eiectscobtained are-.fnifiyCnlvIzn-i4 group where-meis.janeinteger not greaterf thert'rillustratedibytheeaccompanying drawings tha-nllY-inf'a quantityvwhicn'alone is insulicient e Whichzshow spectralfsensitiyity--rcurves,fortheto impart any fsubstantialfcolour'sensitivityA toeirrnlsiions;` oflcertaini of thesioi-Legoing examples;V theeinulsion-andvwhiohismot greater thanJ/iof; These draWingsiarefas-follovvs: y Y Y and notless than-l/lmof thelweight of-.the `pseudo- 6.: ,A photographicgelatino silverbromide -emulzi sionvv containing a pseudocyanine. dye selected f 7 from the-@class consisting of Oxa-,- thiaand" .E iigE lib. f A -Y ggg selena-pseudocyaninefdyes;off0,05 to.0.1 gram.4 i Kamp e: @L Xampe' 70' 10litresotemulsiontogether'with a thiaf-i E 13.12 isb.v per' Y I H Egxglgflgf :Eglggbr carbocyanine siibstitutedsin the-9pors1t1on by a pmipge iai mamme Dh CnHm-rgroup Where isan integer net greater 5 k; f Y c Y than Llfinaquantityflifhoh alone isffinsucient to Itwillibe.iappreeiatedthat the :process nitride-inf impart anyA substantial. coloure sensitivity tothee vention^` presents: the; :,clear/ advantage eover `tlrief 75 emulsion andv which is fnotfgreatei"A than ,1/40 and z f j riiiim lLemoine 5 not less than 17620 of the Weight of the pseudocyanine dye present.

7. A photographic gelatino silver iodobromide emulsion containing a pseudocyanine dye selected from the class consisting of oXa-, thiaand Selena-pseudocyanine dyes in a quantity which alone is sufficient to impart good colour sensitivity to the emulsion, together with a 9-alky1 thiacarbocyanine dye in a quantity Which alone is insucient to impart any substantial colour sensitivity to the emulsion and which is not greater than jzo and not less than tzo of the weight of the pseudocyanine dye present.

8, A photographic gelatina silver iodobromide emulsion containing a pseudocyanine dye selected from a class consisting of oXa-, thiaand selena-pseudocyanine dyes in a quantity of 0.05 to 0.1 gram per 10 litres of emulsion, together with a 9-a1ky1 thiacarbocyanine dye in a quantity 6 which alone is insufficient to impart any substantial colour sensitivity to the emulsion and which is not greater than tn and not less than Jygo of the Weight of th-e pseudocyanine dye 5 present.

ERNEST EDWARD fNICI-IOLSON. RONALD BERNARD COLLINS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 

